Tsukatsuki Rio

Tsukatsuki Rio (調月リオ, Tsukatsuki Rio) is one of the students studying at Millennium Science School who wields a Handgun. She is the president of Seminar, and is the main antagonist of the second half of Volume 2, and later a supporting character on Volumes Final and EX.Rio is the student council president of Millennium. Cold and calculating, she cares more about objective facts than emotions. She is at odds with Himari due to their contrasting personalities. Her nickname is "Big Sister."Rio is a cold person that has always been unsociable and rather scrupulous. She never lets emotions change her mind and always sticks to the facts. Her determination to identify and analyze potential threats to Millennium and Kivotos at large has led her to develop an extensive surveillance system as a result. This in turn has caused her to gain a terrifying reputation among Millennium's student body, which she personally ignores. Rio is also very determined when it comes to reaching her goals, even breaking the rules if she has to.She uses a black Springfield Armory M1911 Mil-Spec pistol with gray grips. The Millennium insignia is etched on the forward slide.